Corrosion wear behaviors of 2024Al in artificial rainwater and seawater at fretting contact

The fretting wear behaviors of an aluminum alloy 2024Al flat specimen against a 440C stainless steel counter ball specimen were evaluated in distilled water, artificial seawater and rainwater by using a ball-on-flat configuration with 300 μm amplitude at room temperature for 1 h. Potentiodynamic anodic polarization was used to measure the corrosion behaviors of 2024Al before and after the corrosion wear test. The worn surfaces of the specimens were observed using scanning electron microscopy (SEM). The valence of the elements on the wear scars was detected by X-ray photoelectron spectroscopy (XPS). The 3D-morphology and wear volume-loss were determined using a non-contact optical profilometer. The influences of the frequency and aqueous mediums on the friction coefficient and wear loss were analyzed. Results show that the friction coefficient decreases generally with the frequency increasing in the three aqueous solutions. The friction coefficient decreases 21.47% in rainwater and 47% in seawater compared with that in distilled water. This indicates the considerable influence of aqueous solutions on the friction coefficient due to the lubricative film formed on the 2024Al specimens. However, the wear loss in both the corrosive solutions is always larger than that in distilled water due to the erosion effect of chlorine ions on the wear scar. Wear loss increased in distilled water, increased more in rainwater, and increased even more in seawater; this demonstrates a positive synergism between corrosion and wear. The contribution of synergism (ΔV) to total wear loss (V) of 2024Al reveals that the synergism is worse in seawater than in rainwater. The wear mechanism of 2024Al is dominating abrasion wear in rainwater, whereas it becomes corrosion fatigue in seawater.